Composition of baths and additives for electrodeposition of bright zinc from aqueous,alkaline,electroplating baths

ABSTRACT

It has been found that the addition of the reaction product of a 1-halo-2, 3-epoxypropane and an amine selected from the group consisting of secondary and tertiary cycloaliphatic amines to aqueous, alkaline electroplating baths containing zinc ions, provides smooth, bright deposits of zinc.

Unlted States Patent [1 1 {111 3,803,008 Rosenberg et al. I Apr. 9, 1974 l l COMPOSITION OF BATHS AND ADDITIVES FOR ELECTRODEPOSITION 0F BRIGHT [56] References Cited ZI FR Q ALKALINE, UNITED STATES PATENTS ELECTROPLATING BATES 2,791,554 5/1957 Winters 204/55 Y [75] Inventors: William E. Rosenberg, Parma; 3227633 1/1966 Bumso" 204/55 Y X Herbert Geduld, University 3,655,534 4/l972 Kampc 204/55 R Heights, both of Ohio Priman Examiner-G. L. Kaplan [73] Asslgnee: Hun & Atmrnev, Agent, or Firm-Watts, Hoffman, Fisher &

Cleveland, Ol'llO Heinke' [22] Filed: July 27, 1972 211 App]. No.: 275,534 [571 ABSTRACT It has been found that the addition of the reaction 'f i Apphcatlon Data product of a l-halo-Z, 3-epoxypropane and an amine [63] commuauon'm'pan of selected from the group consisting of secondary and 1971' abandoned" tertiary cycloaliphatic amines to aqueous, alkaline electroplating baths containing zinc ions, provides [52] U.S. Cl. 204/55 Y, 204/DIG. 2, 204/55 R th h d f 51 Int. Cl. C23b 5/10, C23b 5/46 t 5 5 [58] Field of Search 204/55 R, 55 Y, 432, 44 4 Claims, N0 Drawings CROSS-REFERENCES TO RELATED APPLICATIONS This application is a continuation-in-part of our copending; application Ser. No. 116,649, filed Feb. 18, 1971, now abandoned.

BACKGROUND OF THE INVENTION This invention pertains to improvements in the electrodeposition of zinc from aqueous, alkaline plating baths.

The electroplating of bright zinc coatings fromaqueous, alkaline baths containing 7.5 to 150 gms. of sodium cyanide per liter is commonly achievedat present through the use of many widely knownaddition agents. However, the removal of the poisonous cyanide from the rinse water and sewage as required by law and health regulations can be carried out only at a very great expense, and;the required safety measures render zinc plating by means ofcyanide containing baths so expensive that in many cases it can no longer be carried out economically.

The widely known-addition agentsthat provide bright deposits of zinc from alkaline, cyanide containing plating baths have little or no effect in the cyanide-free, a11- kaline baths. The deposits obtained in this case are dark, and spongy above a current density of 10 amps. per square foot; Witi -v this invention, bright electrode-. posits can be obtained'at a current density range of from to over 150 amps per square foot, with or without the use of sodium cyanide. This wide current density range and elimination of the need for poisonous cyanide in the bath provides a novel, practical method of producing bright electrodeposits of zinc.

SUMMARY OF THE INVENTION The present invention comprises an aqueous, alka-.

line electroplating bath, for producing a bright, lustrous, electrodeposit of zinc, containing zinc ions, and dissolved therein ata concentration of about 0.01 to about gms. per liter, the reaction product of a lhalo-.2, 3-epoxypropane and a substance selected from the group consisting of secondary and tertiary cycloaliphatic amines, of the following general formulae:

DETAILED DESCRIPTION T he reaction products of a l-halo-2, 3-epoxypropane and a substance selected fromthe group consisting of secondary and tertiary cycloaliphatic amines of the following formulae:

where n is 1 to about 2,000, R is hydrogen or hydroxymethyl and R is hydrogen, hydroxy or piperazino are not at present available in commerce. Howevenall of the reactant are readily available or are easily synthesized and the reaction is easily accomplished with excellent reproducibility. The reactants that are not available in commerce are the cycloaliphatic amines where R and R are not hydrogen. These reactants are made by simply adding stoichiometric amounts of formaldehyde to solutions of piperazine at room temperature with mixing. The reactants. are added to a vessel equipped'with a reflux condenser and enough water to obtain one molar concentration. The reaction mixture is stirred vigorously and heated at reflux until a clear singlephase is obtained. The mole-ratio of l-halo-2, 3- epoxypropane to amine can vary from about 0.5/1 to about 2/1. The following examples will further demonstrate this preparation:

EXAMPLE I:

60 gms. of N-methyl piperazine is added to a vessel containing 660 ml. of water. The solution is heated to 140F., with stirringand 92 gms. of epichlorohydrin is added dropwise over a 35 minute period. Upon completion of the addition of epichlorohydrin, the mixture is heated to reflux and stirred for 1 hour. The solutionis then allowed to cool, giving a clear, light yellow liquid of approximately 1 molar concentration.

The reaction products of this invention may be used in combination with any of the widely used brightening agents, e.g., gelatin, glue, peptone, anisaldehyde, piperonal, veratraldehyde, vanillin, 3-substituted-N-alkyl pyridinium halide, and quaternary aliphatic amines, said brighteningagents being presentin amounts from ab0ut 0.005 to about 5 gms. per liter. The brightening compositions of this invention are preferably used in the form-of aqueous addition agents andcontain from about :1 to about 1:100 parts by weight of the reaction product.

While the addition agents of this invention are effective in many aqueous, alkaline zinc plating bathformulations, it is preferred to use any of the basic baths described in the following examples. It'will be understood that the following examples are just illustrations and are notmeant to limit the use of the invention to these bath compositions only.

EXAMPLE II Bath Composition Concentration gms/liter epichlorohydrin and N-methyl piperazine at 1 molar concentration EXAMPLE in Bath Composition Concentration gms/liter Zinc Oxide 5 Sodium Hydroxide 75 Reaction product of N- 2 Methyl Piperazine and cpichlorohydrin at l molar concentration Veratraldehyde 0.l

EXAMPLE IV Bath Composition Concentration grns/liter Zinc Oxide 9 Sodium Hydroxide 75 Reaction product of 2 epibromohydrin and N- methyl piperazine at 1 molar concentration EXAMPLE V Bath Composition Concentration gms/liter Zinc Oxide 9 Sodium Hydroxide 75 Reaction product of 2 epibromohydrin and N- methyl piperazine at 1 molar concentration Anisaldehyde 0.1

All testing was done in a conventional 267 ml. Hull Cell using steel panels and a zincanode. Two ampere 4 the same, and having set forth the best mode contemplated of carrying out this invention, we state that the subject matter which we regard as being our invention is particularly pointed out and distinctly claimed in what is claimed, it being understood that equivalents or modifications of, or substitutions for, parts of the above specifically described embodiment of the invention may be made without departing from the scope of the invention as set forth in what is claimed.

What is claimed is:

1. An aqueous, alkaline, electroplating bath for producing a bright, lustrous electrodeposit of zinc, containing zinc ions, and dissolved therein about 0.01 to about 10 gms. per liter of a reaction product obtained by the reaction of a l-halo-Z, 3-epoxypropane and an amine at about a 0.5/1 to about 2/1 mole ratio of halo epoxypropane t0 amine, the amine being selected from the group consisting of secondary and tertiary cycloaliphatic amines of the following general formula;

where n is about 1 to about 2,000, R, is hydrogen or hydroxymethyl, and R is hydrogen, hydroxy or piperazino, at a reaction temperature of about 140 F. to reflux for about 1 hour and a sufficient amount of water to give about a 1 molar solution. i

2. A bath composition as set forth in claim 1 wherein there is also dissolved up to about 150 gms. of sodium cyanide per liter.

3. A bath composition as set forth in claim 1 wherein the l-halo-2, 3-epoxypropane is epichlorohydrin.

4. The plating bath composition as set forth in claim 1 wherein there is also present at least one of the substances selected from the group consisting of gelatin, glue, peptone, anisaldehyde, piperonal, veratraldehyde, vanillin, a 3 substituted -N-alkyl pyridinium halide and a quaternary aliphatic amine and present in a concentration of about 0.005 to about 5 gms. per liter. 

2. A bath composition as set forth in claim 1 wherein there is also dissolved up to about 150 gms. of sodium cyanide per liter.
 3. A bath composition as set forth in claim 1 wherein the 1-halo-2, 3-epoxypropane is epichlorohydrin.
 4. The plating bath composition as set forth in claim 1 wherein there is also present at least one of the substances selected from the group consisting of gelatin, glue, peptone, anisaldehyde, piperonal, veratraldehyde, vanillin, a 3 substituted -N-alkyl pyridinium halide and a quaternary aliphatic amine and present in a concentration of about 0.005 to about 5 gms. per liter. 